Nexus 1000V interfaces not forwarding

Martin Jaburek · ‎12-13-2011

Hi all,

I have a problem, that interfaces shows as up, but it does not actually work - it doesn't work.

When I tried vemcmd show port:

LTL VSM Port Admin Link State PC-LTL SGID Vem Port

18 Eth4/2 UP UP F/B* 0 vmnic1

49 Veth7 UP UP FWD 0 vmk0

50 Veth13 UP UP FWD 0 Nexus1000V-4.0.4.SV1.3d.eth2

51 Veth12 UP UP FWD 0 Nexus1000V-4.0.4.SV1.3d.eth1

52 Veth10 UP UP FWD 0 Nexus1000V-4.0.4.SV1.3d.eth0

53 Veth1 UP UP FWD 0 uda20.eth0

54 Veth8 UP UP FWD 0 Nexus1000V-4.0.4.SV1.3d (Second

56 Veth3 UP UP FWD 0 Nexus1000V-4.0.4.SV1.3d (Second

* F/B: Port is BLOCKED on some of the vlans.

How can I found out which vlan is blocked?

mipetrin · ‎12-13-2011

Hi Martin,

If you wish to verify what vlans are on each port, execute:

# vemcmd show port vlans

It is normal to see that statement about BLOCKED vlans, if you are not allowing all possible vlans.

You stated that it doesn't work. What symptoms are you seeing to say it doesn't work?

From your output, it is only reporting for vmnic1.

What vlans are you allowing on the upstream switch port connected to this vmnic?

The port-profile for this vmnic allows which vlans?

If you could be more specific about what isn't working, we can help.

Thanks,

Michael

Martin Jaburek · ‎12-13-2011

Hi Michael,

my setup is that I have two servers connected via switch (which does not understand vlans), essentialy I have only one data vlan 104. The whole setup was working, but then I tried upgrade to 4.2.1(4a) and now I lost connectivity to that vlan (VMs and VSM mgmt0)

Maybe the problem is with the native vlan on that trunk (here it says number 1):

[root@exs-x86demo9 ~]# vemcmd show port vlans

Native VLAN Allowed

LTL VSM Port Mode VLAN State Vlans

18 Eth4/2 T 1 FWD 5,10,104

49 Veth7 A 104 FWD 104

50 Veth13 A 10 FWD 10

51 Veth12 A 104 FWD 104

52 Veth10 A 5 FWD 5

53 Veth1 A 104 FWD 104

54 Veth8 A 10 FWD 10

56 Veth3 A 5 FWD 5

and configured port-profile for eth4/2:

port-profile Rack4Uplink

type: Ethernet

description: taggedUplink

status: enabled

max-ports: 32

min-ports: 1

inherit:

config attributes:

switchport mode trunk

switchport trunk native vlan 104

switchport trunk allowed vlan 5,10,104

no shutdown

evaluated config attributes:

switchport mode trunk

switchport trunk native vlan 104

switchport trunk allowed vlan 5,10,104

no shutdown

assigned interfaces:

Ethernet4/2

Ethernet6/1

Ethernet6/2

port-group: Uplink_Rack4

system vlans: 5,10

capability l3control: no

capability iscsi-multipath: no

port-profile role: none

port-binding: static

Martin Jaburek · ‎12-13-2011

I just added vlan 104 to the system vlans section on the Rack4Uplink and now it works. But I don't know why it should not work...? (show module showed all modules and both VSMs)

Martin Jaburek · ‎12-13-2011

interesting thing is, that now the command show port vlans display the native vlan correctly as 104:

Native VLAN Allowed

LTL VSM Port Mode VLAN State Vlans

18 Eth4/2 T 104 FWD 5,10,104

49 Veth7 A 104 FWD 104

50 Veth13 A 10 FWD 10

51 Veth12 A 104 FWD 104

52 Veth10 A 5 FWD 5

53 Veth1 A 104 FWD 104

54 Veth8 A 10 FWD 10

56 Veth3 A 5 FWD 5

305 Po1 T 104 FWD 5,10,104

mipetrin · ‎12-13-2011

Hi Martin,

I can see that you have configured the control VLAN as 5, management as 104, and packet as 10.

The control VLAN is where most of the communication takes place, that allows the VSM to see the VEM (as in your output of show module).

In your initial configuration, you correctly defined the control and packet VLANs as system vlans. However, the management VLAN should also be a system VLAN to ensure that it is always forwarding (even after a reboot of the VSM and prior to it coming back up), as this is an important VLAN for you to manage the VSM itself. Although, this is mainly important when the VSM is behind a VEM. In this scenario, if you don't define it as a system vlan, then you can run into traffic disruption as you have experienced.

Further details regarding system vlans and their use can be found in previous posts on the forums. Good place to start:

https://supportforums.cisco.com/thread/2012512

Thanks,

Michael